Add in first go at near breach sla status.
Rename the function so it's easier to find.
Modified near breach calculation

I have added a near_breach_date field to issues and modified the
save_due_date code to also work out the near_breach_date.
Adding near breach colour and prioritising pause
Merge pull request #87 from alexlatchford/alexlatchford-near-breach2

Alexlatchford near breach2